The present invention relates to an arrangement for height adjustment of seats, particularly power vehicle seats.
Arrangements of the above mentioned general type are known in the art. In a known arrangement, a seat support is connected with rails associated with the vehicle bottom, wherein the front end region of each lateral supporting member is connected respectively via a swinging member with a toothed rack with the associated rail in pivotable manner, and a pinion is supported in each lateral support member and engages with the toothed rack. The pinions are arranged on a shaft extending through the lateral support members and fixable in stepped manner via an actuatable locking device together with the seat support in selectable height positions. One such arrangement is disclosed, for example, in the German Offenlegungsschrift 2,926,450. The seat support in this arrangement is supported in its rear region so that it can be turned about a horizontally extending axis relative to the rails associated with the vehicle bottom. In the front region a horizontally displaceable shaft extends through the seat support and has ends which are connected for joint rotation with the respective pinions. The pinions engage in the toothed racks of two swinging members supported on the rails, whereby a turning movement of the seat support relative to the rails is possible in a tension-free manner. For fixing the height position of the seat support, a locking device is retained in a shaft which is horizontally displaceable in the lateral support members. This locking device includes substantially locking pipes extending at both sides in the front seat region from the rails associated with the vehicle bottom. They have arcuately curved elongated openings which extend to the rear pivot point and have locking recesses extending towards the front side at different heights for receiving the shaft ends overlapping the pinion. For horizontal displacement of the shaft ends in the lateral support members, a lever system is provided which acts via an accumulator for automatically bringing a locking position of the shaft in the locking recesses. This locking position is released by a handwheel, whereby the seat support in its front region can be lifted or lowered. The swinging pipes at both sides are formed so that the toothed pinion is in constant engagement with the fixed toothed rack on each swinging pipe and a synchronous lifting movement at both lateral support members takes place. With this known arrangement, the front seat region can be lifted or lowered when desired, whereas the seat support and therefore the seat in its rear region substantially remains in its height position. In many cases, however, it is desirable to provide a possibility to adjust the seat in its height position universally to the requirements of the user. For this purpose a height adjustment of the rear seat region is also required.